Fracture toughness measurement of mild steels with reinforced-double-cantilever-beam specimen

1976 ◽  
Vol 11 (4) ◽  
pp. 195-201 ◽  
Author(s):  
C L Chow ◽  
R C Owen
Keyword(s):  
Fracture Toughness ◽  
Crack Propagation ◽  
Cantilever Beam ◽  
Double Cantilever Beam ◽  
Graphical Representation ◽  
Crack Opening ◽  
Beam Specimen ◽  
Opening Displacement ◽  
Extension Force ◽  
Tension Testing

The fracture toughness of mild steels was successfully determined under monotonic and cyclic crack propagation. The conditions governing the valid measurement of fracture toughness were satisfied by r.d.c.b. (reinforced-double-cantilever-beam) specimens, and photomicrographic evidence and compliance measurements verified the yielding of the specimens during cracking confined to the crack tip. Measurements of fracture toughness of EN 24 (BS 970 817M40) steel were made on the r.d.c.b., c.o.d. (crack-opening displacement) and c.k.s. (standard tension testing) specimens and the results verified the validity of the r.d.c.b. testing method. The compliance measuring approach was used to determine the rate of fatigue crack propagation and was found satisfactory using the graphical representation based on change in crack extension force Δ G. It was observed that the grain size of the steel has definite effects on its fracture toughness.

A double cantilever beam incorporating cohesive crack modeling for superconductors

2020 ◽  
Vol 34 (15) ◽  
pp. 2050166 ◽  
Author(s):  
K. F. Wang ◽  
Y. Q. Wang ◽  
B. L. Wang ◽  
L. Zheng
Keyword(s):  
Cantilever Beam ◽  
Electromagnetic Force ◽  
Double Cantilever Beam ◽  
Crack Opening ◽  
Cohesive Crack ◽  
Opening Displacement ◽  
Cohesive Interface ◽  
Potential Applications ◽  
Space Solar Power ◽  
Separation Relation

In this paper, a double cantilever beam (DCB) specimen incorporating cohesive crack is developed for superconductors which have potential applications in high temperature superconducting cables in space solar power station. The cohesive interface is introduced along the crack front of the DCB model under electromagnetic force. The load-separation relation (i.e. the crack opening displacement) is used as the fracture mechanics parameter and the corresponding curves during fracture process are obtained and verified by the finite element numerical method. Results show that the presence of tensile electromagnetic force makes crack propagate easily. Superconductors with small cracks have good adaptability to the oscillation of magnetic fields while that with large cracks are easier to fracture during the descent of the magnetic field. In addition, the ductility ratio of the cohesive interface can significantly increase the fracture strength. The length of fracture zone decreases as the crack length increases.

Influence of the Crack Opening Rate on the Fracture Toughness of Plain Concrete

1985 ◽  
Vol 64 ◽  
Author(s):  
P. Rossi ◽  
C. Boulay ◽  
P. Acker ◽  
Y. Malier
Keyword(s):  
Fracture Toughness ◽  
Brittle Fracture ◽  
Cantilever Beam ◽  
Double Cantilever Beam ◽  
Crack Opening ◽  
Plain Concrete ◽  
Elastic Behavior ◽  
Linear Elastic

ABSTRACTThree D.C.B. tests (Double Cantilever Beam) under different loading histories have shown that the applied crack opening rates can have an effect on the KIC fracture toughness values computed on the basis of linear elastic behavior of concrete. This assumption can be well justified for a certain range of crack opening rates, outside of which viscous phenomena must be taken in account. The concepts of ductile and brittle fracture appear then as related to the crack opening rate.

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